In recent years, certain high performance bicycles have included hydraulic disc brakes. Hydraulic disc brake systems typically include a caliper housing, a first movable brake pad and a second fixed or movable brake pad. The movable brake pad is typically attached to a piston that is movable in response to fluid pressure applied via a hydraulic fluid conduit in the caliper housing. The brake pads are positioned on either side of a rotor, which is attached to the front or rear wheel of a bicycle. Upon the application of fluid pressure to the piston or pistons, the brake pads come into contact with the rotor, thereby applying frictional resistance and causing the bicycle to slow down or stop.
Hydraulic disc brake systems for bicycles are typically actuated by a brake lever attached to a bicycle handlebar. They also typically include a master piston in a master cylinder which is actuated by the brake lever. The master cylinder contains a hydraulic fluid and is in fluid communication with the disc brake caliper via a fluid conduit. The brake pads are typically spaced apart from the rotor by a predetermined gap. As the lever is contracted towards the handlebar, the master piston moves, thereby forcing liquid out of the master cylinder and into a conduit connected to the caliper housing. The movement of fluid into the caliper housing causes the pistons to move, eventually bringing the brake pads into contact with the rotor. Once the brake pads contact the rotor, they provide frictional resistance which can be increased by further operation of the lever. At this point, the caliper housing is fully pressurized, and further operation of the lever increases the system hydraulic pressure and frictional resistance applied to the rotor.
When operating hydraulic disc brake systems, no braking will occur until the brake pads come into contact with the rotor. Thus, there is a “dead band,” as the rider begins to contract the brake lever during which no braking occurs. To compensate for the dead band, riders may initially contract the brake lever quickly to obtain pad to rotor contact and then more slowly to increase the frictional resistance to the desired level. As a result, braking is not smooth. Also, a hydraulic brake system may include a left side lever for a rear disc brake caliper and a right side lever for a front disc brake caliper (or vice-versa). When the left and right side levers operate at the same time, both front brake pads and rear brake pads do not contact the rotors at the same time. In other words, the levers are uneven when the pads contact the rotors.
In addition, certain known systems have an adjustable dead band. However, in many of these systems, the lever's reach is affected by variations in the dead band. Conversely, certain known systems include an adjustable reach feature. However, many of them do not allow for adjustment of the dead band, or if they do provide for dead band adjustment, it cannot be made without affecting the lever's reach.
Thus, a need has arisen for a hydraulic disc brake lever which addresses the foregoing problems.